This invention relates generally to injection molding and more particularly to hot runner apparatus having improved cooling provided by the circulation of cooling fluid through spaced openings in a front portion of an elongated core.
The cycle time of hot runner injection molding systems can be reduced by providing increased cooling to the cavity. Reducing cycle time by even a fraction of a second is very important in large volume applications such as making closures with millions or even billions of moldings. As seen in U.S. Pat. No. 5,094,603 to Gellert which issued Mar. 10, 1992, it is well known to provide the mold with a cooled core by circulating cooling water through a central cooling tube in the core. While this is satisfactory for many applications, there is still a considerable delay in the molding cycle before the mold is opened for ejection waiting for the melt to solidify. As the front portion of the cooled core forms part of the cavity, improved cooling must be achieved without unduly reducing the structural strength of this front portion of the cooled core.